Electrical selector.



L. C. BYGRAVE.

ELECTRICAL SELECTOR.

APPLICATION FILED FEB-8.1916.

1,226, 1 84. Patented May 15, 1917;

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IMF- M L 1.1 1.4 L. 85; liar; I l 1 l r Inveniarr UNITED STATES PATENTOFFICE.

LEONARD CHARLES BYGRAVE, OF LONDON, ENGLAND, ASSIGNOR TO THE RELAYAUTOMATIC TELEPHONE COMPANY, LIMITED, 01 LONDON, ENGLAND.

ELECTRICAL SELECTOR.

To all whom it may concern:

Be it known that I, LEONARD CHARLES BY- GRAVE, a subject of the King ofGreat Brit'- ain, residing at Marconi House, Strand, London, England,have invented new and useful Improvements in Electrical Selectors, ofwhich the following is a specification.

The invention relates to electrical selec tors or impulse respondersconsisting of relays which are energized in succession to select acertain circuit. The principal objects of the invention are to simplifythe circuits of the selector and to reduce the number of relays requiredfor a given number of selective positions.

The invention is illustrated panying drawing. of the invention havingone switching relay for each selective position and Fig. 2 shows aselector in which the number of switching relays is less than the numberof selectable lines.

by the accomrelay A. The selective impulses are sent over an impulsewire W from-an impulse transmitter, here represented by a key K.

A release key K controlling the locking circuits of the relays R, isclosedv before the impulses are sent.

Upon the first impulse being sent, A is energized over a circuitextending through back contacts B of all relays R. A, upon operating,connects itself through its contact C directly to W and closes at itscontact D the circuit of the first switching rei lay R which cuts itselfin a locking circuit through its contact E and a contact F on the secondrelay R and prepares the circuit of the latter by closing contact G.\Vhen the first impulse ceases A denergizes and as its operating circuitis now open at contact B of relay R, the second impulse does not affectA, but operates the second relay R over contact B of A, contact Gr ofrelay R and .contact H of relay R RelayR. locks up over a circuitsimilar to that of relay R and prepares the circuit of relay R byclosing its contact G. At the same time the locking circuit of the firstswitching relay is switched over to the impulse wire W at contact L. Inconsequence thereof relay R is denergized upon the cessation of thesecond impulse. In a simi- Speciflcation of Letters Patent.

Figure 1 shows one form The selector shown in Fig. 1 normally PatentedMay 15, 1917.

Application flied February 8, 1916. Serial No. 76,955.

lar manner the third impulse causes the operation of R and thedeenergization of R and so on.

A relay, once deenergized, is evidently not renergized during the samesetting period. The slector is restored to normal position by opening.the key K The selectable circuits, numbered 1 to 6, and here shown assingle wire circuits, are connected to front gontacts of thecorresponding switching reays.

I The selector shown in Fig. 2 consists of seven relays only, but maynevertheless be usedto select .any of ten circuits numbered 1 to 10. Thecircuits of the first six relays are mainly the same as in Fig. 1. therebeing five switching relays R. The seventh relay DR is a differentiatingrelay, operated bythe sixth impulse to switch the impulse circuit backto the starting end of the selector.

The first five impulses operate the selec-v tor in the manner iustdescribed.

The sixth impulse energizes relay DR, which looks itself over itscontact E and remains energized until the selector is restored to normalposition. When the sixth impulse ceases, relay R denergizes and connectsW over the back contacts B of all relays R to relay A. The selector isthereafter operated as before from the starting end by the seventh andfollowing impulses.

The selectable circuits are divided in the manner shown in the drawinginto two groups numbered 1 to 5 and 6 to 10 respectively, a circuit ofthe first group being connected up over a back contact of DR, while acircuit of the second group is connected up over a front contactthereof.

It appears from the above description that after six impulses have beensent, the differentiating relay DR only remains energized, and the sixthcircuit is then connected up over back contacts of all relays R andfront contact of DR.

A selector according to this invention, may be used for selectingcircuits of any kind, but is particularly adapted for automatic andsemi-automatic telephone systems. In such systems, for instance, it maybe employed individually with each talking circuit to hold up a talkingconnection which it has established, or it may be'used in common by aplurality of talking lines and merely select and complete operatingcircuits for relays which make and hold up the connection; or it may beoperated by a first series of impulses to select a group of lines andthen by a second series of impulses to select a particular line of thatgroup and to uphold the connection with said lines. It may also be usedin combination with operators key-sets in semi-automatic systems to'control the transmission of current impulses, in which case the selectoracts in known manner as a counting device to permit a certain number ofimpulses to be sent to the selectors of the exchange.

\Vhat I claim is 1. A selector comprising a series of switching relays,an impulse circuit for energizing the relays in succession and means fordeenergizing a previously energized relay on the interruption of theimpulse energizing the next relay.

2. A selector comprising a series of switching relays, an impulsecircuit for energizin the relays in succession, means whereby eac relayon operating prepares the circuit of the next and means whereby eachrelay on deenergizing extends the impulse circuit to the next relay butone.

3. In an electrical selector, the combination of a starting relay, aplurality of switching relays, an impulse wire, means for transmittingelectrical impulses to such wire, a back contact of each switching relayconnected to a spring of the next succeeding relay, all such backcontacts and springs being normally connected in series with the windingof the starting relay, a front contact of each switching relay beingnormally connected to the winding of the next succeeding relay, one ofthe springs of such next relay being adapted to break such connectionand being connected to a front contact of the succeeding relay, springsof the relays connected to the impulse Wire and adapted to cooperatewith the last mentioned contacts and means for restoring the relays tonormal.

l. A selector comprising a series of switching relays, an impulsecircuit for energizing the relays in succession, means whereby eachrelay after having been operated is deenergized on the interruption ofthe impulse energizing the next relay, said means com prising a holdingcircuit for each relay and means for opening such circuit on thecessation of the impulse succeeding the impulse which caused such relayto be energized.

5. A selector comprising a series of switching relays, an impulsecircuit for energizing the relays in succession, means whereby eachrelay, after having been operated, is deenergizecl' on the interruptionof the impulse energizing the next relay, said means comprising aholding circuit for each relay and means for branching such circuit tothe impulse circuit on the operation of the next relay.

6. A selector comprising a series of switching relays, a number ofselective lines controlled by said relays, an impulse circuit forenergizing the relays in succession and means whereby the selector isautomatically reset after it has been set to a fixed selective position.

7. A selector comprising a series of switching relays, a number ofselective lines controlled. by said relays and arranged in groups, animpulse circuit for energizing the relays in succession and meanswhereby, after the selector has been set to a fixed selective position,a new group of selective lines is automatically switched into selectiveconnection.

8. A selector comprising a series of switching relays, a number ofselective lines controlled by said relays, an impulse circuit forenergizing the relays in succession, means whereby each relay, afterhaving been operated, is deenergized on the interruption of the impulseenergizing the next relay and a differentiating relay operating, afterthe selector has been set to a fixed selective position, to switch theimpulse circuit back to the first relay of the series.

LEONARD CHARLES BYGRAVE.

